S100 Calcium Binding Protein (S100)

A1is a member of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. This protein may function in stimulation of Ca²⁺-induced Ca²⁺ release, inhibition of microtubule assembly, and inhibition of protein kinase C-mediated phosphorylation.

Reduced expression of this protein has been implicated in cardiomyopathies. S100A1 overexpression enhances cardiac contractile performance which suggests that S100A1 is a regulator of myocardial contractility. S100A1 improves cardiac performance both by regulating calcium ion handling by the sarcoplasmic reticulum and the responsiveness of myofibrils to calcium ion.